The main idea of this book is that in addition to commonly accepted Darwinian idea of genetic evolution via random change in DNA followed by selection of organisms fit for environment, there is another mechanism – epigenetically changing genes expression that has tremendous impact on the functionality of organism. Author believes that these two mechanisms are complimentary with epigenetics responsible for quick response to dramatic changes in environment, while DNA changes are much slower and kind of harden new functionality of organism.
INTRODUCTION: Looking Back
It starts with discussion of sci-fi, entertainment, and quick changes that occur in life, technology, and environment requiring similarly quick changes in humans and other animals and their behavior. The usual scientific explanation divides it into two separate domains: Darwinian evolutionary random DNA change with selection of the fit, which is very slow process and cultural change that supplement this selection with quick accommodations. Author believes that it is not enough and does not adequately explain accumulated observation. The missing component is epigenetic change, which practically brings back Lamarckian ideas of biological inheritable changes. Biologically it is done by natural addition of molecules that regulates DNA expression, highly dependent on environment, and is inheritable.
CHAPTER I From God to Science
Here author retells the story of raise and mainly fall of Lamarck’s ideas of acquisition of inheritable characteristics. Somehow instead of just supplemental process in understanding of evolution it became perceived as unscientific. Here author definition of what it is: “The favored theory of Charles Darwin, and the “Darwinians” who followed him, is that the major process of evolution is driven by natural selection combined with genetic change by mutation. Epigenetics posits that a quite different set of circumstances can drive also evolutionary change, and that both Darwinian- as well as epigenetic-driven change (or, to do him honor, Lamarckian-driven change) can proceed simultaneously.
Author also reviews general history of scientific understanding from observation of Hadrian wall leading to rejection of biblical account of geological age, through work on Linnaeus cataloguing living organisms that demonstrated their changeability, and work of Buffon, who anticipated Darwin’s Ideas by about a hundred years, but did not risk to go public with this. Author also briefly discusses Darwin’s grandfather Erasmus who was thinking in similar ways.
CHAPTER II Lamarck to Darwin
This chapter retells story of Lamarck’s live and survival during French revolution. From professional side it is also story of struggle against Georges Cuvier, who in addition to being “father” of comparative anatomy and scientist who developed understanding of mass extinctions was also dedicated enemy of Lamarck who succeeded in discrediting Lamarck’s work.
CHAPTER III From Darwin to the New (Modern) Synthesis
Here author presents Darwin’s view in such algorithmic way:
- There is a pattern of characters encoded in each organism in structures called genes.
- This pattern is copied and passed on to offspring.
- The copying is never perfect: Variations arise through errors in copying or through random (not directed) mutations. This produces variation. Even greater variation is introduced through sexual reproduction.
- The variant members compete with each other for more offspring produced that can survive.
- There is a multifaceted environment that makes some of the variants more successful than others.
- The individuals that survive and go on to reproduce, or who reproduce the most, are those with the most favorable variations. They are thus naturally selected.
This all is correct, but not complete. Author points to the speed with which evolutionary change occurs, making it impossible to explain by random process exclusively. Another problem is the absence of small change sequences for many cases when new species appear seemingly from nowhere.
CHAPTER IV Epigenetics and the Newer Synthesis
This starts with explanation of the modern understanding of epigenetics as a supplemental phenomenon to DNA that changes genes expression without changing DNA itself while allowing these changes to be transferred to the next generation. Author provides example of this with 2 types of nautiluses that were considered different species, but have the same DNA. Then author provides definition: “Epigenetics is the study of heritable gene functions that are passed on from one reproducing cell to another, be that to a somatic (body) cell or to a germ cell (sperm or ovum), which does not involve a change to the original DNA sequence.” The bulk of this chapter discusses how exactly this happens:
- Methylation: DNA activated by methyl groups
- Modification of genes expression, often via interaction of 2 X chromosomes.
- Reprogramming: combination of genome and epigenome.
Then author discusses impact of this new understanding that includes epigenetics impact on history of life and hormonal processes.
CHAPTER V The Best of Times, the Worst of Times—in Deep Time
This is about history of life, how environment had been changing, and how Darwinian random change could not explain speed of change without addition of epigenetics. Author discusses mass extinction events: asteroid 65 million years ago, Siberian Traps 251 million, extinction events between 600 and 700 millions. and the worst for life –snowball Earth 2.5 billion years. In all cases the first response of organisms was epigenetic reorganizations that only later followed by DNA changes. Overall author supports idea of multilayer adaptation to environmental change:“First was the change in environment experienced by an individual organism. Second was a change of that organism’s behavior. Third was a change in its phenotype, the expression of not only how its genes were used prior to the environmental change, but also how they are expressed post change. The greater the environmental change, the more consequential each of these steps might have been.“
CHAPTER VI Epigenetics and the Origin and Diversification of Life
This chapter is about a very important problem with origin of live – how come that quite complex DNA molecules were created in the first place. Author discusses what life is: complex organization, metabolisms, replicates, and evolves. In 2016 was discovered LUCA – the last universal common ancestor, which is bacteria like creature with DNA. Theoretical research claims that minimum for life is 355 genes. Author discusses how such complex combination could be created via lateral gene transfer that happens all the time on microbial level. At the end of chapter author discusses the Margulis endosymbiosis theory that proposes increase of complexity via direct merges of different microorganisms under environmental pressure, which would clearly be Lamarckian process.
CHAPTER VII Epigenetics and the Cambrian Explosion
This is discussion of period of rapid expansion of life that author believes could be explained only by epigenetic model:”It is posited here that four different epigenetic mechanisms presumably contributed to the great increase in both the kinds of species and the kinds of morphologies that distinguished them that together produced the Cambrian explosion as we currently know it: the first, the now familiar methylation; second, small RNA silencing; third, changes in the histones, the scaffolding that dictates the overall shape of a DNA molecule; and, finally, lateral gene transfer, which has recently been shown to work in animals, not just microbes.“
CHAPTER VIII Epigenetic Processes Before and After Mass Extinctions
The main point of this chapter is that Darwinian and Lamarckian evolution are different in both their mechanism and in their application, the latter more active during conditions of rapid adjustments to environment often after mass extinction events, while the former is more complex fine tuning process that kind of hardens results in form of DNA:
Author also discusses contemporary mass extinction and links it to domestication.
CHAPTER IX The Best and Worst of Times in Human History
This is about impact of human cultural evolution on human biology. Author discusses cognitive revolution that occurred 70,000 years ago after Toba eruption, then another one some 45,000 years ago with ice age climate change, then the one that came with agriculture, and finally the one that is currently in process. The main point author makes here is that all this happens way too fast for random DNA change to handle, so epigenetics provides more robust framework for this.
CHAPTER X Epigenetics and Violence
This is about more than just link of genes to violence, but rather explanatory insufficiency that exists if one does not brings in epigenetics. Here is example, formulated as three laws of behavior:
- First Law: All human behavioral traits are heritable.
- Second Law: The effect of being raised in the same family is smaller than the effect of genes.
- Third Law: A substantial portion of the variations in the complex human behavioral traits is not accounted for by the effects of genes or families.
CHAPTER XI Can Famine and Food Change Our DNA?
This is continuation of discussion on environmental impact and author uses well-documented historical event of famine in Holland during WWII, that left clear traces in next generation. However author does not limit mechanism of impact here to epigenetics only. He also discusses impact of famine in microbiome that currently more and more considered a necessity for human existence.
CHAPTER XII The Heritable Legacy of Pandemic Diseases
Here author starts with obvious point that pandemics have great impact on gene pool not only by eliminating significant part of it, but also by its influence on survivors. This influence occurs via methylation process, making it transferable to the next generation without changing genetic code. Author also points to intensive religious experience prompted by pandemics and even specifies gene VMAT2, which controls mood and seems to be susceptible to epigenetic changes.
CHAPTER XIII The Chemical Present
This is about simple chemical impact of multitude of different toxins and metals that also could have influence that appears to have epigenetic effect.
CHAPTER XIV Future Biotic Evolution in the CRISPR-Cas9 World
This is about amazing finding that humans evolved in the last 5000 years as much as in precious 6 million years. This was done based on DNA analysis in 270 people from different genetic groups. The conclusion author derives is that dramatic change in environment accelerates evolution and epigenetics provide explanation for this process so far. However now humans are getting close to intentionally modifying genetic material to achieve specific results and this would practically switch process of human development from evolution to production.
EPILOGUE Looking Forward
Here author looks in the future and is quite scared by what he sees, which is increase in stress, all kinds of catastrophic events, referring to the paleontological research that found marks of increased stress in animals in areas where humans moved. Similarly stress in Native Americans dramatically increased with arrival of Europeans. Now the stress is increasing for the whole humanity, causing epigenetic change. Author ends with the point that epigenetic is moving into mainstream and probably will become quite common approach with the passing of older generation of scientists who cannot overcome old paradigm.
MY TAKE ON IT:
I think that idea of epigenetics and non-DNA inheritable change makes lots of sense and, if experimentally confirmed, does lead to the new synthesis in understanding of evolution. I personally would like to see the general theory of evolution that would include not only Darwinian and Epigenetic changes, but also cultural changes. After all the example of discovery of use of fire, while being obviously cultural event seems to lead overtime to purely biological changes in human digestive system that in term provided a lot more time for developing brain, language, and development of sophisticated culture, making humans not only super predators, but also unchallenged force in shaping the world to their convenience.